Field of the Invention
Embodiments of the present invention generally relate to a base ring assembly for use in a substrate processing chamber.
Description of the Related Art
Semiconductor substrates are processed for a wide variety of applications, including the fabrication of integrated devices and microdevices. One method of processing substrates includes depositing a material, such as a dielectric material or a conductive metal, on an upper surface of the substrate. For example, epitaxy is a deposition process that grows a thin, ultra-pure layer, usually of silicon or germanium on a surface of a substrate. The material may be deposited in a lateral flow chamber by flowing a process gas parallel to the surface of a substrate positioned on a support, and thermally decomposing the process gas to deposit a material from the gas onto the substrate surface.
The chamber design is essential for film quality in epitaxy growth which uses a combination of precision gas flow and accurate temperature control. Flow control, chamber volume, and chamber heating rely on the design of a base ring, which is typically disposed between a top dome and a lower dome (defining a processing volume for a substrate) and dictating the layouts of the process kit and inject/exhaust caps which in turn influence the epitaxial deposition uniformity. Conventional epitaxy chamber is very tall, resulting in there being a large distance between the top and bottom domes and the substrate. This results in highly non-uniform flow, turbulence, eddy currents, and an overall large chamber volume. The chamber volume limits the ability of the system to run in transient, deposition-etch switching mode and requires long chamber stabilization time, which restricts process uniformity with sudden changes in cross sectional area over the substrate which negatively influences flow uniformity, induces turbulence, and affects overall uniformity of deposition gas concentration over the substrate.
Since flow characteristics directly impact the film performance on the substrate, there is a need for a deposition apparatus which provides a balanced and uniform flow field throughout the process chamber.